Objective: Because of the high uptake of 18FDG in brain, its disadvantage in brain lesion PET imaging, [18F]Fluoroethyl-dimethyl-2-hydroxyethylammonium (18FECH) background uptake in brain was low, it could improve the sensitive and specificity of brain lesions diagnosis.We analysed the false positive and false negative in 18FECH PET imaging in brain lesions with the aim of improving the accuracy of diagnosis with 18FECH PET imaging.Methods: 38 patients with brain lesion were studied using 18FDG PET and 18FECH PET/CT brain imaging.The diagnoses of all patients were verified by biopsy or operation under neuronavigation guidance, and pathology including immunohistochemistry.It was considered a positive result that increased tracer uptake relative to the surrounding background radioactivity in 18FECH PET/CT imaging, the maximum standardized uptake value (SUVmax) for lesion and peritumoral regions was measured, and a lesion-to-normal tissue uptake ratio (LNR) was calculated, LNR >2 that was considered a positive result.There were eleven false negative and false negative.Results: 1.Five were false positive (one tuberculous granuloma, one necrosis of cerebral infarction, one pilosity hardenability gliocyte proliferation, one hemorrhage caused by vascular malformation and one demyelination).2.Six were false negative (one dysembryoplastic neuroepithelial tumor, two grade Ⅱ glioma, one grade Ⅱ oligodendroglioma, one grade Ⅱ oligoastrcytoma and one grade Ⅲ anaplastic oligoastrcytoma).Conclusions: 18 FECH PET/CT clearly revealed the location and extent of the tumors ,and had a role in qualitative diagnosis, but had a certain rate of false positivity and false negativity.